[babel-plugin] Optimize dynamic styles output

[mellyeliu]

Follow up to https://github.com/facebook/stylex/pull/1153

There are times in which we don't need to emit a ternary wrapping dynamic styles when we can confirm the expression is not null or undefined. We have coverage for binary and unary expressions, but there are a few more cases we can optimize for:

• template literals
• conditional exprs (recursively check both sides)
• logical expressions like
  • nullish coalescing ?? (if left side is safe)
  • logical or || (if either side is safe)
  • logical && (both sides are safe ie. a string/binary/unary/template literal of course).

May be missing some cases

[mellyeliu]

• same treatment for the inline styles portion